Sixty votes were needed to allow the bill to be debated on the Senate floor, but Republicans refused to allow the bill to come up for debate after complaining Democrats weren't allowing votes on their amendments. Sen. Angus King, I-Maine, also broke with his typical party leanings and voted with Republicans against cloture. The vote was 53-44, with Majority Leader Harry Reid, D-Nev., joining Republicans as a "no" in order to preserve his right to reconsider the vote.

King explained his vote in a lengthy statement. "This particular bill, in my view, fails to address the real causes that are driving the wage gap," he said. "In addition, the bill could impose substantial burdens on businesses in justifying pay differentials," he said, adding that there are better ways, like raising the minimum wage, to address the gap.

No Republican voted with the Democrats. Three Republicans did not vote: Tom Coburn of Oklahoma, John Cornyn of Texas and Ted Cruz of Texas. Republicans also blocked debate on the pay measure in 2010 and 2012.

Senate Republican women had proposed their own alternative by Sens. Deb Fischer of Nebraska, Susan Collins of Maine, Kelly Ayotte of New Hampshire and Lisa Murkowski of Alaska that would have included provisions against retaliating against workers who inquire about salaries.

Republicans had also sought to get votes on other proposals that they said would boost jobs.

"When the Obamacare economy is already hurting women so much, this legislation would double down on job loss all while lining the pockets of trial lawyers," said Minority Leader Mitch McConnell, R-Ky. "In other words, it's just another Democratic idea that threatens to hurt the very people that it claims to help."

"Though we lost the vote, we refuse to lose the battle," said Sen. Barbara A. Mikulski, D-Md., immediately after the vote. She said they would not give up on the effort and urged women to put their "lipstick on" and continue the fight.

Reid ripped the GOP's move in advance.

"Are Republicans in the Senate so repulsed by equal pay for hard-working American women that they can’t even stomach the thought of debating the issue?" he asked. "Instead, Republican senators have come to the floor and tried to offer amendments that have nothing to do with equal pay. As I said yesterday, if senators wish to offer amendments to the Paycheck Fairness Act, they first need to vote to begin debate on the bill."

King's full statement is here:

“Discrimination of all kinds is wrong. I think a woman ought to get paid as much as men for the same work – that’s just common sense and it’s the law. But I’ve looked at this from all sides – I’ve talked to Mainers, to business leaders, to men and women, and this particular bill, in my view, fails to address the real causes that are driving the wage gap. In addition, the bill could impose substantial burdens on businesses in justifying pay differentials. The way to narrow the wage gap between men and women includes facilitating more family-friendly workplaces, which will allow women to stay in the workforce if they choose to have children; encouraging more girls and young women to pursue higher-paying professions, like science, engineering, law, and medicine; and improving the earning potential for low-wage workers, who are disproportionately women. That’s why I support raising the minimum wage, which the President’s Council on Economic Advisers says will help narrow the wage gap. I support equal pay for equal work, and this was a very difficult vote. In the end, however, I felt this bill will not get us there – and I look forward to working with my colleagues on legislation that will.”